Series: How to do a 13849-1 analysis

Func­tion­al safety is all about the like­li­hood of a safety sys­tem fail­ing to oper­ate when you need it. Under­stand­ing Mean Time to Dan­ger­ous Fail­ure, or MTTFD, is crit­ic­al. If you have been read­ing about this top­ic at all, you may notice that I am abbre­vi­at­ing Mean Time to Dan­ger­ous Fail­ure with all cap­it­al let­ters. Using MTTFD is […]

What is Dia­gnost­ic Cov­er­age? Under­stand­ing Dia­gnost­ic Cov­er­age (DC) as it is used in ISO 13849 – 1 [1] is crit­ic­al to ana­lys­ing the design of any safety func­tion assessed using this stand­ard. In case you missed a pre­vi­ous part of the series, you can read it here. In the last instal­ment of this series dis­cuss­ing MTTFD, I brought up the […]

What is a Com­mon Cause Fail­ure? There are two sim­il­ar-sound­ing terms that people often get con­fused: Com­mon Cause Fail­ure (CCF) and Com­mon Mode Fail­ure. While these two types of fail­ures sound sim­il­ar, they are dif­fer­ent. A Com­mon Cause Fail­ure is a fail­ure in a sys­tem where two or more por­tions of the sys­tem fail at the same time from a single […]